Halliday & Matthiessen (1999: 568):
There is thus a range of variation from our everyday folk models to scientific models, with expert models somewhere coming in between (Linde, 1987). Such models vary considerably in the degree to which we are consciously aware of them as models. We are more aware of models that ‘stand out’ as belonging to a particular subculture than those that are part of our everyday repertoire; and we are more aware of scientific models than of folk models.